Accelerating device for alternating-current motors.



W. 1). LUTZ. AGGEDERATING DEVICE FOR ALTERNATING CURRENT MOTORS. APPLICATION IILED JAN. 7, 1911.

1,0721 32. Patented Sept. 2, 1913.

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W. D. LUTZ. AGGELBBATING DEVICE FOR ALTERNATING CURRENT MOTORS.

. APYLICATION FILED JAN. 7, 1911 1,072,1 32, Patented Sept. 2, 1913.

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WILLIAM D. LUTZ, 0F ALLENDAL'E BOROU GH, NEW JERSEY, ASSIGNOR TO OTIS ELE- VATORv COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF N EW' JERSEY.

ACCELERATING DEVICE FOR ALTERNATING-CUmENT MOTORS.

Specification of hitters Patent.

Application filed January 7, 1911.

Patented Sept. 2, 1913. Serial N 0. 601,427.

To all whom, it may concern:

Be it known that I, WILLIAM D. LU'rz, a citizen of the United States, residing in the borough of Allendale, in the county of Bergen and State of New Jersey, have lnvented a new and useful Improvement in Accelcrating Devices for Alternating --C.urrent Motors, of which the following is a spec1fi-; cation.

My invention relates to motor control and more particularly to the acceleration of an' alternating current motor.

In accelerating a motor ,it is usually desired that the motor be brought up to full speed as rapidly as possible, and for different loads the acceleration should be in proportion to the speed of the motor instead of being dependent for operation upon a dashpot action or upon the passage of a cer- 2 tain interval of time. The magnetic effect of two transformer windings or of the windings of an induction coil may be so opposed that if the effect of one-is varied the resultant current may be employed rtO ener-' gize a magnet orseries vof magnets.

The current taken byan alternating current motor is' largest in starting, gradually decreasing as the motor accelerates, .and at full speed the current taken is the minimum amount. In View of this characteristic, the magnetizing efiect of the motor current .is opposed to the efiect induced in'anot her winding in such a way that when the motor, starting there is no resultant effect of the; decreases, .the F magnetic efi'ect in the other winding becomes greater and may be utilized .to energize a single device .or several devices in succcs-L sion.

'The pnincipal object of my invention isj to util'zethe' above stated characteristic in? providing means to accelerate a motor in;

proportion to the speed thereof .rgardless of 1 29 and mcreasmg the load on ,the motor.

In the accompanying drawings, Figure 1 shows my invention in conjunction with a motor making use .of an inductioncoil with opposed windings. Fig. 2 shows :the same employing two transformers with opposed secondary windings.

Referrin now more particularly to ,F

is-shown having slip rings K for the rotor .wuiding, sectional starting recient sistance R, accelerat ng W6 A, C, i

' main switch S, inductive device I, and a brake device L connected to the motor mains. The motor M is connected to the main switch S by the motor leads 15, 16, 17, a few turns L9 of one lead, as 15, being wound around the core 18 of the inductive device I. The

accelerating magnets operate groups of contacts a, b, c and d to short circuit portions of the resistance R which is connected to the rotor winding through the slip-rings K. The energizing circuits for the magnets are all completed through a winding 29 on the core 18. A circuit for the winding 11 is traced from the motor lead 16 through winding '29, conductor 30, winding 11, conductor 31, contacts 21, 25,27, conductor 32 to motor lead 17. When the magnet A operates contacts 20 are joined and complete a circuit through the next magnet winding 12; the operation of magnet B separates the contacts 21 thereby opening the circuit of {the magnet winding 11, connects the con- -tacts 22, 23 to establish a circuit to the winding 13 of magnet C; magnet C in turn opens the windingcircuit of magnet B and closes a circuit through magnet winding 14 of magnet D; magnet D when energized opens the magnet wi-ndi circuit of magnet C and establishes a holing circuit for its own energization through contacts 28. The winding 29 is first in series with winding 11 and both are connected across the motor leads 16 and 17 The winding 29, however, is wound about the core 18 so that when a current of suflicient strength flows in winding 19 it induces an electro-motive force of such a potential that the voltage applied to the terminals of winding 11 is not 'sutlito actuate the magnet. As soon as the motor M starts, the current in the lead 15 is reduced, and the inductive effect of the winding 19 is less, thereby lessening the opposing electro the potential applied to an e rtentthat It .is-op- The operation .of this :a portion ,of the rotor wind' 11 to such erative y energized.

magnet short-circuits starting resistance R the next magnet winding 12, resulting .in acceleration of the motor Maud a fiurther decrease in current in the motor lead 15 ,and

winding 19, and when this decrease a predetermined value the next in petated- .In this my t e ac l m reaches motive force in winding and closes a circuit to Y I at is n .qi.

"led step by In -Fi 2 iiic general arrangementis the some as shown by Fig. L the 51cc crating magnets, E, F, G and ii having than. Wind iuge 3. 3 and connected in perahci and receiving current from transformers i and t by way of conductors i0 and iii C f the two iIflilSfOI'H'lGlE-I i and L" ine first has for its primary Winding a number of turns 19 of the moiior ieaei 15, and the second has a primary Winding 3" connected across the motor mains iii and 1'7. The secondary windings 38 and 39 are connected in series and in opposition, so that the magnet windings are subject only to the difference of potcntiai induced in the two secondary windings, This diiiercnce varies because the 20 eIc ct-ro-motive force induced in the windings 38 (iireciiy proportional co the current in the Winning 19, which decreases as the speed. of the motor increases, while the induced eleciroonotive force in. the winding 39 is oiw eys substantially the some. The

magnet E is operetively energized iirec, then as the speed of the motor Increases and the diiierence in potential between the two windings 3S and 39 increases, the next mag- SQ net F is operated cutting the magnet Winding 33 by its operation. The contacts 7 a, b, c" and d are joined by the magnets in succession, to short-circuit port-ions of tho aeceierating resistance until it is all out out. and the motor runs at full speed.

it is obvious that various changes could "be made in the arrangement and detail of paris herein sgvrmh. For instance, the Severn inductive circuits oouiii be connectm n to he various phases so as to comone of the motor leads, another in iceivive' winding connected across iAiO motor lieads, receiving a potential egucl to or prooorsionai to that of the said leads, and opposing it; eiiect to that of the first Said winding, and inductive de 'ces depcnent for energizat-ion upon the c ifierence in ogiposing eiiect.

2' The combination with an eitcrneting current moior of an inductive winding through which one moior iced is ocmnccie'i another inciuciniie win ing conneeiefi ccrose two motor lwzis are? crossing iis cfiect to for,

the first winding, zinc? magnets energized and successively operated by a current which flows when the opposing eiiect varies.

3. The combination with an alternating current motor, of an inductive Winding con ncctcd to vary the inductive efi'cct with tr e mocor current, another inductive Winding connected to the motor leads and having a enbsalifiieiiy constant inductive effect, and means dependentfor energization upon the (iifi'ereuce in the induciive effects of the two wimiings. P

4. The combina'iion with an alternating current motor, of an inductive winding connected io vary the inductive efi'ect in no 0 cordnnce with the current of the motor as thfhSpBBii increases, another Winding of substentiaily constant inductive effect opposcii thereto and eiaztroniagnets succcssiveiy co crated by currentdetermincd by the difierenee in inductive efiec-t as the motor spemi increases.

5. The combination with an alternating current motor of an induciive Winding in one of the motor iE-rldS varying its ineiuctive efl'eci; inverse-1y as the speed of the motor varies, another Winding connecied across the motor leads with Substantiaily constant inductive effect opposed to the first, and magnets of different strcn h dependent for energizamon upon the (11 erence of inductive efieci between the two windings, this difference varying directly as the motor speed.

7, The combination with an alternating current motor of an inductive winding in one of the motor leads varying its inductive effect inversely as the speed of the motor varies, another incluctive Winding with inductive effect substantially equal to that of the first winding when the motor starts anci exceeding it when the motor accelerates, and magnets dependent for energizetion riiroetly upon the difierence of in duciaiie efiects and energizcci in succession as the speed of the motor increases. A

S. The combination of an alternating currentmot r, an accelerating resistance therednotive winding connected in a motor lea-d, he inductive: efi'ect. decreasing BEIGE, tho differen -e of inductivge efiect-s and es the motor speed increases, another iii-- operative to short-circuit portions of the said resistance.

9. The combination of an alternating current motor, accelerating apparatus therefor, means to supply current to said apparatus independently of the motor, and inductive means governed by the current supplied to the motor to vary the current to said ap-.

paratus in response to variation in the current supplied to the motor.

10. The combination of an alternating current motor, accelerating magnets, and inductive means to differentially vary the current to the said magnets as the current to the motor varies.

11'. The combination of an alternating current motor, accelerating magnets receiving current in a. circuit separate from the motor, and inductive means to vary said current in response to variations in current through the motor.

copies of thin patent may be obtained for 12. The combination of an alternating current motor, electroresponsive accelerating mechanism, and tan inductive device comprising a winding connected in circuit between the motor and source of current supply and a winding in the circuit of said electroresponsive mechanism.

13. The combination of an alternating current motor, starting resistance therefor, electromagnets controlling said resistance, a circuit for said magnets connected across two of the motor leads, and an inductive device com rising a coil in one of the motor leads an a coil in said magnet circuit.

In testimony whereof, I have signed, my name to this specification in the presence of two subscribing witnesses.

WILLIAM D. LUTZ.

Witnesses:

' EDWARD H. STEELE,

GEORGE D Rosa.

five cents each, by addressing the Commissioner of Patents, 

